departed vs past

departed and past both are nouns.

Word	Noun	Adjective	Verb	Adverb
departed	Yes	Yes	No	No
past	Yes	Yes	No	Yes

departed (noun)	past (noun)
someone who is no longer alive	a verb tense that expresses actions or states in the past
	the time that has elapsed
	a earlier period in someone's life (especially one that they have reason to keep secret)

departed (adjective)	past (adjective)
dead	earlier than the present time; no longer current
well in the past; former	of a person who has held and relinquished a position or office

departed (adverb)	past (adverb)
	so as to pass a given point